Physical vapor deposition (PVD) in semiconductor fabrication is typically performed with a target made of a desired film material. In the case of alloys, the targets are typically composed of the alloy to be sputtered. In the case of new non-volatile memories, alloys of different compositions are used. As such, the inventors are investigating co-sputtering of multiple targets in a multi-cathode (e.g., multi-target) PVD chamber. However, because of the cross-contamination of the multiple targets, the targets are cleaned periodically to maintain film consistency. For example, one or more of the multiple targets may be covered by shutters during the cleaning process, which may lead to particle generation.
Therefore, the inventors have provided embodiments of methods and apparatus for improved co-sputtering of multiple target materials in a PVD processing system.